NASA Releases The First-Ever Images Of Our Solar System's Tail

For the first time astronomers have observed our solar system's
tail using NASA's Interstellar Boundary Explorer, or IBEX.

Our sun releases a stream of charged particles, called solar
wind, that forms a bubble around our solar system known as the
heliosphere. IBEX mapped the boundaries of the tail of this solar
bubble, called the heliotail.

The tail is made up of fast- and slow-moving particles, which
scientists determined by stitching together three years of images
beamed back by IBEX.

This data from NASA’s
Interstellar Boundary Explorer shows what it observed looking
down the solar system’s tail. The yellow and red colors represent
areas of slow-moving particles, and the blue represents the
fast-moving particles.NASA/IBEX

"Many models have suggested the heliotail might be like this or
like that, but we’ve had no observations," principal investigator David McComas said in a
statement. "We always drew pictures where the tail of the
heliosphere just disappears off the page, since we couldn’t even
speculate about what it really looked like."

Looking straight down at the tail, it appears to be in the shape
of a four-leaf clover. Slow-moving particles make up the the two
side leaves, while fast-moving particles make up the top and
bottom leaves. The whole shape is slightly twisted, suggesting
it's being influenced by the magnetic field from another galaxy
as the tail moves away from the sun's magnetic field.

"This shape makes sense, given the fact that the sun has been
sending out mostly fast solar wind near its poles, and slower
wind near its equator for the last few years — a common pattern
in the most recent phase of the sun’s 11-year activity cycle,"
NASA explains.

Astronomers have long-believed that our solar system, like a
comet, has a tail that trails behind it. The particles in the
tail don't shine so it's hard to spot them using conventional
telescopes.

IBEX uses a technique called energetic neutral atom imaging. The
instrument collects neutral atoms created by collisions at the
boundary of the heliosphere. The resulting neutral atoms can take
several years to hit IBEX. Because the particles move in a
straight line, however, they can provide clues about the original
charged particles. Scientists can map out the particles to create
a picture of what's happening in far-off regions.